java - 类型集不带参数

Question

package set;

import java.util.*;

public class Set 
{

  public static void main(String[] args)
  {
    String [] things = {"appple", "bob", "ham", "bob", "bacon"};
    List<String> list = Arrays.asList(things);

    System.out.printf("%s ", list);
    System.out.println();

    Set<String> set = new HashSet<String>(list);
    System.out.printf("%s ", set);

  }

} 

当我尝试运行这个程序时，我的 set 声明总是出现这个错误。我做错了什么？

Answer 1

重命名您的 public class Set分类为不隐藏的名称 java.util.Set .

您的定制Set类不接受任何类型参数。这就是为什么 Set<String>没有通过编译。

例如:

package set;

import java.util.*;

public class SetTest 
{
    public static void main(String[] args)
    {
        String [] things = {"appple", "bob", "ham", "bob", "bacon"};
        List<String> list = Arrays.asList(things);

        System.out.printf("%s ", list);
        System.out.println();

        Set<String> set = new HashSet<String>(list);
        System.out.printf("%s ", set);  
    } 
}